Theodoee michaut



NITED STATES PATENT OFFICO THEODORE MIOHAUT, PIERRE OONNOY, AND FRANK J. WIEST, OF BOULDER CITY, COLORADO.

PROCESS FOR REDUCING ORE.

SPECIFICATION forming part of Letters Patent No. 389,161, dated September 4, 1888.

Serial No. 224,460. (Specimens) To all whom it may concern.-

Be it known that we, THEODORE MioHAUr, PIERRE CONNOY, and FRANK J. WIEsT, of Boulder City, in the county of Boulder and State of Colorado, have invented a new and Improved Process for Reducing Ores,of which the following is a full, clear, and exact de scription.

The object of our invention is to provide certain new and useful improvements for reducing or desulphurizing auriferous pyrites and other sulphurous ores.

The process consists of mixing the pulverized ores with a compound consisting of feldspar, carbonate of lime, silicon, potash, and fire-clay, and then subjecting the mixed mass to heat in a roastingfnrnace.

Heretofore in smelting or reducing ores, especially gold and silver ores combined with sulphuret of iron or iron pyrites, the sulphur contained in the ores rendered the lat ter very refractory, so as to impair their value by preventing a recovery of the valuable metals or making the recovery very expensive. Such refractory ores are generally roasted; but this process has not been found to be very effective in removing or destroying the sul" phur sufficiently so as to render the resulting mass economically tractable in the subsequent reduction ofthe metallic substances contained in the mass.

With our improved process we are enabled to free the above-mentioned ores and also tellurinm from the sulphur, and we accomplish this result by pulverizing and mixing the ores with a compound consisting of the following ingredients, which are thoroughly mixed in a dry state and pulverized by roll eis or other means: feldspar, ten parts, carbonate of lime, ten parts; silica, twenty-five parts; carbonate of potassa, five parts, and fireclay, fifty parts. About fifty pounds of this compound are mixed with one hundred pounds of ore of middle or low grade; but when the ore is richer-such as highgrade telluriumwe use from sixty-five to seventy-five pounds of the compound to one hundred pounds of ore.

In practice we generally pulverize the compound and the ore together in the same machine, whereby the several ingredients are thoroughly mixed. The resulting mass is then put into a roasting-furnace of any approved construction and roasted from three to live hours, according to the quantity and nature of the mass. \Vhen the mass is subjected to heat of 1,100 to 2,000 Fahrenheit, it increases in bulk and becomes a sticky mass, inclosed, as it were, with a coating, thereby permitting the escape only of the vapors of the base metals and retaining the gold and silver in the refuse of the ore.

The operator can ascertain when the process is completed by taking a small quantity out of the furnace. If the mass taken out is entirely red when cold, then the process is tin ished; but when black or black spots still appear on the mass, then the process is not completed, and the mass must be further subjected to heat.

The mass must be stirred up in the furnace while the roasting is going on. When the roasting is completed,the gold and silver are in a free and native state, and are either amalgamated or chlorinated, as desired. If the ores or compound are wet, they must be dried before being placed in a roasting-furnace.

\Ve prefer to use the above-described compound as it is found in the natural state, on account of its cheapness and the facility with which it can be obtained; but we do not restrict ourselves tosucluasitis evidentthat the several ingredients may be obtained, separated, and mixed together with equally asgood results.

Having thus fully described our invention, we claim as new and desire to secure by Letters Patent- The herein-described process for desulphurizing ores, consisting of mixing the pulverized ores with a pulverized compound consisting of feldspar, carbonate of lime, silica, carbonate of potassa, and fire-clay, and then subjecting the mixed mass to heat, substantially as shown and described.

THEODORE MIOHAUT. PIERRE OONNOY. FRANK J. \VIEST.

\Vitnesses:

'1. J. GRAHAM, WILLIAM GROSECLOSE. 

